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SDL library in C/C++ with examples
  • Last Updated : 09 Mar, 2021

SDL is Simple DirectMedia Layer.It is a cross-platform development library designed to provide low level access to audio, keyboard, mouse, joystick, and graphics hardware via OpenGL and Direct3D.It can be used to make animations and video games.  

  • It basically provides a set of APIs to interact with various devices like graphics hardware, audio, keyboard, mouse, etc. 
  • It is written in C programming language and works with C++ and various other languages like c# and python. 
     

Installation on Linux ( For OS which uses the apt package manager eg : Ubuntu ): 

  1. Run command sudo apt-get update on your terminal. 
     
  2. Run command sudo apt-get install clang on your terminal. 
     
  3. Run command sudo apt-get install libsdl2-2.0-0 libsdl2-dbg libsdl2-dev libsdl2-image-2.0-0 libsdl2-image-dbg libsdl2-image-dev on your terminal. 
     
  4. We need to make a Makefile.So open a text editor of your choice and start writing the code below. 
# A simple Makefile for compiling small SDL projects

# set the compiler
CC := clang

# set the compiler flags
CFLAGS := `sdl2-config --libs --cflags` -ggdb3 -O0 --std=c99 -Wall -lSDL2_image -lm
# add header files here
HDRS :=

# add source files here
SRCS := #file-name.c

# generate names of object files
OBJS := $(SRCS:.c=.o)

# name of executable
EXEC := #name your executable file

# default recipe
all: $(EXEC)
 
showfont: showfont.c Makefile
    $(CC) -o $@ $@.c $(CFLAGS) $(LIBS)

glfont: glfont.c Makefile
    $(CC) -o $@ $@.c $(CFLAGS) $(LIBS)

# recipe for building the final executable
$(EXEC): $(OBJS) $(HDRS) Makefile
    $(CC) -o $@ $(OBJS) $(CFLAGS)

# recipe for building object files
#$(OBJS): $(@:.o=.c) $(HDRS) Makefile
#    $(CC) -o $@ $(@:.o=.c) -c $(CFLAGS)

# recipe to clean the workspace
clean:
    rm -f $(EXEC) $(OBJS)

.PHONY: all clean

Header Files:  

CPP




// for initializing and sutdown functions
#include <SDL2/SDL.h>
 
// for rendering images and graphics on screen
#include <SDL2/SDL_image.h>
 
// for using SDL_Delay() functions
#include <SDL2/SDL_timer.h>

Initialization: 

CPP




#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <SDL2/SDL_timer.h>
 
int main(int argc, char *argv[])
{
 
    // retutns zero on success else non-zero
    if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
        printf("error initializing SDL: %s\n", SDL_GetError());
    }
    SDL_Window* win = SDL_CreateWindow("GAME",
                                       SDL_WINDOWPOS_CENTERED,
                                       SDL_WINDOWPOS_CENTERED,
                                       1000, 1000, 0);
    while (1)
        ;
 
    return 0;
}

That will create a empty window on your screen. 
Output: 
 



We will write a simple program to explain rendering and I/O handling: 

CPP




#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <SDL2/SDL_timer.h>
 
int main(int argc, char *argv[])
{
 
    // retutns zero on success else non-zero
    if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
        printf("error initializing SDL: %s\n", SDL_GetError());
    }
    SDL_Window* win = SDL_CreateWindow("GAME", // creates a window
                                       SDL_WINDOWPOS_CENTERED,
                                       SDL_WINDOWPOS_CENTERED,
                                       1000, 1000, 0);
 
    // triggers the program that controls
    // your graphics hardware and sets flags
    Uint32 render_flags = SDL_RENDERER_ACCELERATED;
 
    // creates a renderer to render our images
    SDL_Renderer* rend = SDL_CreateRenderer(win, -1, render_flags);
 
    // creates a surface to load an image into the main memory
    SDL_Surface* surface;
 
    // please provide a path for your image
    surface = IMG_Load("path");
 
    // loads image to our graphics hardware memory.
    SDL_Texture* tex = SDL_CreateTextureFromSurface(rend, surface);
 
    // clears main-memory
    SDL_FreeSurface(surface);
 
    // let us control our image position
    // so that we can move it with our keyboard.
    SDL_Rect dest;
 
    // connects our texture with dest to control position
    SDL_QueryTexture(tex, NULL, NULL, &dest.w, &dest.h);
 
    // adjust height and width of our image box.
    dest.w /= 6;
    dest.h /= 6;
 
    // sets initial x-position of object
    dest.x = (1000 - dest.w) / 2;
 
    // sets initial y-position of object
    dest.y = (1000 - dest.h) / 2;
 
    // controls annimation loop
    int close = 0;
 
    // speed of box
    int speed = 300;
 
    // annimation loop
    while (!close) {
        SDL_Event event;
 
        // Events mangement
        while (SDL_PollEvent(&event)) {
            switch (event.type) {
 
            case SDL_QUIT:
                // handling of close button
                close = 1;
                break;
 
            case SDL_KEYDOWN:
                // keyboard API for key pressed
                switch (event.key.keysym.scancode) {
                case SDL_SCANCODE_W:
                case SDL_SCANCODE_UP:
                    dest.y -= speed / 30;
                    break;
                case SDL_SCANCODE_A:
                case SDL_SCANCODE_LEFT:
                    dest.x -= speed / 30;
                    break;
                case SDL_SCANCODE_S:
                case SDL_SCANCODE_DOWN:
                    dest.y += speed / 30;
                    break;
                case SDL_SCANCODE_D:
                case SDL_SCANCODE_RIGHT:
                    dest.x += speed / 30;
                    break;
                default:
                    break;
                }
            }
        }
 
        // right boundary
        if (dest.x + dest.w > 1000)
            dest.x = 1000 - dest.w;
 
        // left boundary
        if (dest.x < 0)
            dest.x = 0;
 
        // bottom boundary
        if (dest.y + dest.h > 1000)
            dest.y = 1000 - dest.h;
 
        // upper boundary
        if (dest.y < 0)
            dest.y = 0;
 
        // clears the screen
        SDL_RenderClear(rend);
        SDL_RenderCopy(rend, tex, NULL, &dest);
 
        // triggers the double buffers
        // for multiple rendering
        SDL_RenderPresent(rend);
 
        // calculates to 60 fps
        SDL_Delay(1000 / 60);
    }
 
    // destroy texture
    SDL_DestroyTexture(tex);
 
    // destroy renderer
    SDL_DestroyRenderer(rend);
 
    // destroy window
    SDL_DestroyWindow(win);
     
    // close SDL
    SDL_Quit();
 
    return 0;
}

That will render a image on the window which can be controlled via your keyboard up, down, left, right. 
Output: 
 

References: https://www.libsdl.org/, https://github.com/vivek9236/rocket_game
 

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